More Chinese flights have been temporarily grounded, after airline officials reported receiving threats.

Air China said it delayed two of its Beijing-bound flights, from Lhasa and Nanchang, due to threats made in phone calls. Security officials checked both planes and the flight from Lhasa was allowed to depart.

Monday, a China Southern Airlines flight was forced to make an emergency landing in Gansu province's Lanzhou city after getting a threat.

Police searched the plane and detained a man suspected of making the threat.